Surfaces having color directional reflectance properties are present, for example, in metallic paints, iridescent surfaces and in nacreous structures. In such surfaces, not only is the amount but also the spectral distribution of the reflected radiation dependent upon direction. From goniophotometric measurements on such surfaces, it is known that measurements of the reflected radiation at three different angles is required to determine a sufficient correspondence between the comparison specimen and the measured specimen.
U.S. Pat. No. 4,479,718 discloses a measuring device for measuring paint containing metallic flakes wherein a light source illuminates the surface at an angle of incidence of 45.degree.. Three detectors are providced for detecting the reflected radiation and these detectors conjointly define respective angles of 15.degree., 45.degree. and 110.degree. with the radiatio regularly reflected at an angle of 45.degree..
This known measuring device has the disadvantage that the specimens to be measured have to be brought to the measuring device and must be placed adjacent a measuring opening. This is, for example, not possible in the case of an automobile chassis or structural siding.